Some of the criticism was launched even before the president returned home, violating an American political tradition, famously articulated by the late Republican Sen. Arthur Vandenberg of Michigan, that "politics stops at the water's edge."

On his first trip as president to the region, Obama acted according to what he explained could be called the Obama Doctrine -- recognizing that while the United States is the strongest nation on earth, it needs to work with other countries, that cooperation will ultimately benefit the United States and that the country needs to confess to its sins when it fails to meet up to its ideals.

But the moment that took the spotlight -- and probably drew the most criticism -- was his handshake with Venezuelan President Hugo Chavez, who has openly denounced U.S. foreign policies, once called President Bush "the devil" and has often rallied the region in criticizing the United States. At the summit, he even presented Obama with a book assailing the United States for exploiting Latin America.

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Obama approached the Venezuelan president to shake his hand, and the two seemed quite collegial in photographs Chavez rushed to post on his country's Web site. Obama's critics chided the president for smiling widely and touching Chavez on the shoulder as they shook hands.

"You have to be careful who you are seen joking around with. It was irresponsible of the president to be seen joking around with the president [Chavez]," said Sen. John Ensign, R-Nev., former chairman of the National Republican Senatorial Committee, to CNN Sunday morning while Obama was conducting meetings in Trinidad.

On Monday, well after Obama's return, former Republican House Speaker Newt Gingrich of Georgia said Obama's interaction with Chavez sends a poor message to U.S. foes.

"What I find distressing is that the administration opposes opening up oil exploration," he said on NBC's "Today Show." "But yet Obama has bowed to the king of Saudi Arabia and now reached out to Chavez," who has been conducting a "a vicious anti-American campaign."

The White House said Obama was only being courteous, and the president himself scoffed at any idea that his being polite to Chavez played into his hands in any way.

"I think it's just that President Chavez is better at positioning the cameras," Obama joked.

"It is possible we will begin evaluating the designation of an ambassador in the United States," Chavez announced Saturday. "We want to move in that direction. We take Obama at his word, with the one difference we have: We are socialists."

The State Department said Chavez approached Secretary of State Hillary Clinton, and the two discussed returning ambassadors to their respective posts in Caracas and Washington.